1. Field of the Invention
The invention relates to a desiccant-containing package for use in an integrated condenser/receiver, and more particularly, to a desiccant-containing package comprising a porous desiccant bag (most preferably, a desiccant-containing packet or bag) secured to a rigid member.
2. Description of the Prior Art
Desiccant-containing packages have been employed in small diameter receivers that are juxtaposed along one of the condenser headers in an integrated condenser/receiver for an automotive air-conditioning system or the like. These integrated condenser/receiver structures eliminate the need for separate tubing to connect the condenser with the receiver and have become popular due to their reduced spatial requirements as compared with earlier designs. For instance, the overall dimensions of one integrated condenser/receiver proposed in U.S. Pat. No. 5,813,249 [hereinafter the “'249 patent”] are from about 300 mm-400 mm in height and about 300 mm-600 mm in width.
In the integrated condenser/receiver design proposed in the '249 patent, the axes of the receiver canister and the associated header lie parallel to that of the canister attached to, and contiguous with, the header. The desiccant-containing package positioned in the receiver dries refrigerant fluid (and the oil and moisture entrained therein) before the dried refrigerant enters a supercooler unit formed integrally with the condenser. Ultimately, the desiccant material is spent, that is, saturated with contaminants, and must be replaced.
U.S. Provisional Patent Application 60/178,595, the disclosure of which is incorporated herein by reference, discloses a desiccant containing package comprising a pouch preferably formed from a tube of porous polyester felt material. During manufacture, one end of the tube is sealed, preferably by tucking a portion of the tube side wall and flattening the end portion under conditions which cause the polyester fibers to fuse together and seal the end of the pouch. Desiccant material then is poured into the pouch. Most preferably, the open end of the pouch then is ultrasonically welded to an attachment ring of filter cap.
It can be difficult to insert, position and remove such desiccant bags from the receivers of known integrated condenser/receivers due to the compactness of the receivers. In particular, many known receiver designs require the removal and disposal of significant extraneous material with spent desiccant bags, thereby increasing the expense associated with the replacement of the spent bags.
U.S. Pat. No. 5,666,791 proposes an insert for a vehicle air conditioner. The insert is composed of two parts. One part contains a filter screen. The other part is an extension part bridging the distance from the filter screen to a detachable cover of the receiver.
According to the patent, the part which contains the filter screen and which requires higher manufacturing expenditures may be standardized for several sizes of condensers so that it can be produced in the same shape in large piece numbers. Depending on the size of the receiver, the part containing the filter screen is supplemented by an extension part which has a relatively simple shape and can therefore be produced at a reasonable price in different lengths by means of a modular-construction tool. In addition, it is taught that the construction reduces the amount of waste to be disposed of when the desiccant is spent because it will be sufficient to exchange and dispose of the part with the filter screen.
Nevertheless, the insert as a whole is likely to be relatively complex and expensive to produce. In one embodiment taught in U.S. Pat. No. 5,666,791, the container is provided on the inside with a supporting screen. The container, which is made of plastic, is molded around this supporting screen. The supporting screen may consist of plastic or of a special steel, the former having the advantage of being recyclable. In addition, it appears that a filter screen comprising a filter nonwoven material or a needle felt is assembled into the container. This mode of manufacture involves multiple component parts and several manufacturing steps, the combination of which likely increases the cost of manufacture.
U.S. Pat. No. 6,170,287 proposes that a tube of desiccant material be installed and located within a receiver canister by a stand-off comprised of a tight-fitting, notched, disk-shaped base and a narrow central post which is comparable in length to the height of the inlet above the lower end cap. The tight fit allows the tube to be inserted up into the canister, well away from the bottom of the canister and free of heat damage as an end cap of the canister is attached. Later, in operation, the central post keeps the tube located clear of inlet and outlet ports of the canister.
U.S. Pat. No. 6,360,560 proposes a condenser with an integral receiver dryer. The receiver dryer includes a dryer capsule for removing moisture from the refrigerant fluid. One drawback to the dryer capsule proposed in the reference is its relative complexity and likely expense of manufacture.
The dryer capsule proposed in U.S. Pat. No. 6,360,560 is generally cylindrical in shape and includes a base, a housing extending axially from the base and a cap closing an end of the housing. The base is disposed adjacent a seat wall to create a seal and prevent fluid from passing therebetween. The housing has a plurality of apertures extending therethrough and a filter covering the apertures. The dryer capsule includes a quantity of dryer material such as desiccant disposed within the housing. The cap has a loop with an aperture extending therethrough to allow a tool to engage the loop to remove the dryer capsule from the receiver dryer. The loop also acts as a spring to hold the base of the dryer capsule against the seat wall when an end closure is in place over an open end of the receiver dryer.
The end closure proposed in U.S. Pat. No. 6,360,560 has a head extending radially and a threaded shaft extending axially. The end closure also includes a seal disposed about the threaded shaft and adjacent the head. The threaded shaft engages the threaded open end such that the seal engages the side and the head overlaps the side bounding the open end.
It is known to place a fluorescent tracer dye wafer or the like in the desiccant package so that leaks in the refrigeration system can be readily detected by use of an ultraviolet light source. See for instance U.S. Pat. Nos. 5,149,453 and 5,440,910.
There remains a need in the art for improvements to desiccant cartridges for integrated condenser/receivers which simplify the manufacture, installation and removal of the cartridges and which minimize the extraneous material which must be disposed of with spent desiccant bags.